The other thing to do is just go in and talk to the person who has to approve the purchase, talk to the about price limits and all that. Some open discussion can be quite useful, and noting some of the things said here, an Intel Mac can be quite useful for testing OSX/Windows and Linux, even if only to verify the page displays/functions as intended.
I got approval for our helpdesk to get non standard displays, showed my manager how I have to work with everything overlapped on out current 17" company standard LCDs, got approval for 22" widescreens for 8 people (2 not even hired) straight away. So it is only US$2600 total but it will make a significant change in how we can work.
Be open to compromise/discussion and always stay cool, civil discussions always go further